The present invention is directed to pressure surveillance systems, and more particularly to a system for monitoring a pressure-variable biological function such as respiratory pressure at a remote location. The system is particularly useful in monitoring the operation of a ventilator or similar forced-breathing type apparatus.
It is frequently desirable to monitor at a central location one or more pressure-variable biological functions of a patient located at a remote location. This situation arises in large hospitals where a patient located in a general care area must be given special treatment by apparatus requiring continuous or periodic monitoring by specialists at another location in the hospital, or at a nursing home or personal residence where such apparatus must be monitored at a distant hospital or clinic. One treatment frequently administered under these conditions involves the use of forced-breathing or ventilator apparatus, which assist the patient's lungs in maintaining normal breathing. To insure the proper operation of this apparatus it is necessary that the pressure level between the patient and the ventilator be periodically monitored. By analyzing variations in this pressure level the attending physician can ascertain not only that the ventilator is operating properly, but also the condition of the patient's respiratory system. Other pressure-variable biological parameters which can be monitored in this way include spontaneous breathing as measured by a pheumograph, arterial blood pressure, pulmonary functions, and intracranial pressure.
Heretofore, pressure-variable biological functions have been difficult to monitor because of the lack of a suitable transmission medium between the remote patient location and the central monitoring location. While existing telephone lines provide the greatest flexibility as a transmission medium, systems heretofore devised for transmitting pressure-variable biological data on a frequency-modulated carrier tone over such lines utilized laboratory-type equipment for generating the tone, which required a complicated and time-consuming set-up and adjustment prior to each use, and laboratory-type pressure transducers, which were sensitive to shock and temperature variations. Since the environment in which the patient is undergoing treatment is often not conducive to making precise time-consuming adjustments, and since the personnel operating the equipment may not be trained in making such adjustments or may not have sufficient time in the case of an emergency condition, such systems based on laboratory-type equipment have not proven practical for every-day use.
Accordingly, it is a general object of the present invention to provide a new and improved monitoring system for pressure-related biological functions which allows such functions to be monitored over ordinary telephone lines or other audio transmission channels at a location remotely located from the patient.
It is another object of the present invention to provide a new and improved monitoring system for pressure-variable biological functions which does not require adjustment prior to use.
It is another object of the present invention to provide a new and improved monitoring system for pressure-variable biological functions which includes alarm protection against failure of the transmission channel or system components.
It is another object of the present invention to provide a new and improved monitoring system for pressure-variable biological functions which can be utilized in conjunction with ordinary telephone equipment without direct connection thereto or modification thereof.